Caller ID is a telephone on-hook capability that provides a called party with information about the caller before the incoming call is answered. Conventionally, such information includes the date and time of the call and the caller's telephone number. A data message, preceded by a channel seizure signal, is sent in conjunction with the ringing signal from the central office to the called party during the silent interval after the first 20-Hz, 2-second ringing phase.
Caller ID service is designed for use with the voice portion of existing loop connections. The digitally formatted message is transmitted through a stream of data bits of standardized digital format. The message is sent once, without retransmission capability. The channel seizure signal, sent at the beginning of each message to alert the called party equipment of the coming information through physical connection of an appropriate interface, is typically composed of thirty continuous bytes of octal 125 (i.e., 01010101), or 250 milliseconds of a 600-Hz square wave. Transmission of data follows thereafter and is completed prior to the next 20-Hz ringing signal. For a detailed description of the method and apparatus for sending the data message, reference is made to U.S. Pat. No. 4,551,581 issued to Doughty on Nov. 5, 1985.
From the standpoint of a called party subscriber, the caller ID service offers several advantages. Identification of the calling party, as provided by the caller ID service, allows the called party to screen an incoming call personally before its completion and thereby to decide whether or not it is desirable to answer the call. Nuisance calls, such as advertising and solicitation calls, can be avoided if the identity of the caller is determined beforehand. Knowledge of caller identity also serves as a resource for dealing with and curtailing harassment calls.
The caller ID service can be made interactive with a personal computer at the subscriber's station to generate prescribed information related to the calling party for display on the computer monitor as the incoming telephone call is received. Such information can be available thereafter for general operation at the control of the user. A log of caller ID information transmitted with incoming calls over a desired time period may be stored, the information thereby available for future processing. Reference is made to made to U.S. Pat. No. 5,054,055, issued to Hanle et al. on Oct. 1, 1991 for a more detailed description of the intelligent use of caller ID information.
Despite its many favorable aspects, caller ID has raised objections with respect to callers' rights of privacy. If the caller number identity is made known to a called party caller ID subscriber each time a call is made, the privacy afforded to a caller having an unlisted number is significantly compromised. Similarly, any caller may find it desirable to place a call without revealing origination identity to the called party. In such case, the caller must take the risk that the called party line does not subscribe to the caller ID service.
In order to accommodate caller privacy, subscribers have been offered a caller ID block service, whereby the identity of the line originating a call will not be transmitted to the called party. If the called party is an caller ID service subscriber, the display unit will either indicate a caller privacy condition or remain blank. Reference is made to U.S. Pat. No. 5,161,181, issued to Zwick on Nov. 3, 1992, for discussion of this concept. With caller ID blocked, a call is directed to the called party for completion in the standard manner and the functionality of caller ID is lost.
U.S. Pat. No. 5,033,076, issued to Jones et al. on Jul. 16, 1991, proposes to provide a service in which incoming calls to the service customers are screened so that only calls from callers who are willing to have their telephone numbers identified will be received. Such provision would restore protection against nuisance and harassment calls of unidentified origin. In operation, the originating switching system checks each incoming call to determine whether the number of the caller line station is maintained in a privacy status. Such status may be stored in the originating switching system. A standard SS7 message, including a designation of privacy status, is sent to the terminating switch. If the called station will only accept calls from callers willing to provide identification, as recorded in the terminating switch, calls having the privacy status will be blocked from completion, at least temporarily. A message may be sent from either the terminating switch or the originating switch to the caller permitting the caller to override the privacy status for the call.
While the Jones arrangement provides a measure of access protection to the called customer as well as privacy protection to the calling customer, the system lacks flexibility due to functional limitations of the switches. Except for the special case in which the called party is a specified public service facility, there is no treatment for informing the called party that a call from a privacy status caller has been attempted. That is, the Jones system basically treats each such privacy status call as a nuisance or harassment call, blocking completion to the called party.
Further, in the Jones system, considerable additional message transmission signaling is required between the originating and terminating switch for status determination at each end, override prompt announcement, and caller response.
An additional aspect to which the Jones system is not directed is the treatment of caller ID privacy calls in relation to voice messaging. As the number of subscriber message mailboxes continues to increase, the number of advertising messages, the equivalent to "junk mail," delivered to mailboxes becomes a greater nuisance, proliferated by the ability to simultaneously transmit a message for "broadcast" delivery to a plurality of mailboxes. Providing the mail box subscriber with the ability to block such messages, sent from unidentified origin, would alleviate this nuisance problem.
Conversely, forwarding a caller ID privacy call, directed initially to the line of a caller ID subscriber, to a mail box would offer the called party the ability to obtain a message from the caller without having to interact with the caller on line at the time of the call. The called party thus would be spared the potential annoyance of participating in unwanted calls while avoiding the loss of unidentified desirable communications.